Add animation caching, QR scanning workflow, and cache management UI with tests

IMPLEMENTATION_SUMMARY.md

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+# Caching and QR Access - Implementation Summary
+
+## Overview
+
+This implementation provides a comprehensive caching and QR scanner system for the Flutter AR application, following clean architecture principles with proper separation of concerns.
+
+## ✅ Completed Features
+
+### 1. Local Caching Strategy
+- **Cache Service**: Custom implementation with size/TTL policies
+- **Cache Configuration**: 500MB limit, 7-day TTL, max 100 items
+- **Automatic Cleanup**: TTL-based and size-based cache management
+- **File Management**: Efficient file operations with error handling
+- **Storage Location**: Platform-appropriate cache directories
+
+### 2. QR Scanner Workflow
+- **Camera Integration**: Full camera preview with permission handling
+- **QR Code Parsing**: Support for JSON, simple ID, and URL formats
+- **Scanning UI**: Custom overlay with visual feedback
+- **History Management**: Scan history with timestamps
+- **Error Handling**: Graceful degradation for invalid codes
+
+### 3. Cache Management UI
+- **Status Indicators**: Visual progress bars and usage statistics
+- **Cache Info Display**: Real-time cache statistics
+- **Management Actions**: Clear all, optimize, individual deletion
+- **Warning System**: Alerts for cache limits and cleanup needs
+- **Responsive Design**: Mobile-optimized interface
+
+### 4. Offline Fallback Behavior
+- **Cache Persistence**: Survives app restarts and updates
+- **Offline Access**: Downloaded content available offline
+- **Graceful Degradation**: Proper handling of network issues
+
+## 📁 Architecture
+
+### Domain Layer
+```
+lib/domain/
+├── entities/
+│   ├── animation.dart          # Animation entity with caching info
+│   ├── cache_info.dart         # Cache statistics
+│   └── qr_code.dart          # QR code entity
+├── repositories/
+│   ├── animation_repository.dart
+│   ├── cache_repository.dart
+│   └── qr_repository.dart
+└── usecases/
+    ├── download_animation_usecase.dart
+    ├── get_cached_animations_usecase.dart
+    ├── scan_qr_code_usecase.dart
+    ├── get_cache_info_usecase.dart
+    └── clear_cache_usecase.dart
+```
+
+### Data Layer
+```
+lib/data/
+├── datasources/
+│   └── animation_remote_data_source.dart
+├── repositories/
+│   ├── animation_repository_impl.dart
+│   ├── cache_repository_impl.dart
+│   └── qr_repository_impl.dart
+└── services/
+    ├── cache_service.dart
+    └── qr_service.dart
+```
+
+### Presentation Layer
+```
+lib/presentation/
+├── pages/
+│   ├── cache/
+│   │   └── cache_management_page.dart
+│   ├── qr/
+│   │   ├── qr_scanner_page.dart
+│   │   └── qr_history_page.dart
+│   └── media/
+│       └── media_page.dart (updated)
+├── providers/
+│   ├── animation_provider.dart
+│   ├── cache_provider.dart
+│   └── qr_provider.dart
+└── widgets/
+    ├── cache_status_widget.dart
+    └── qr_scanner_overlay.dart
+```
+
+## 🔧 Technical Implementation
+
+### Caching Strategy
+- **Size Management**: Automatic cleanup when exceeding 500MB
+- **TTL Policy**: 7-day expiration with automatic cleanup
+- **LRU Eviction**: Oldest items removed first when needed
+- **File Organization**: Structured cache directory with metadata
+
+### QR Code Support
+1. **JSON Format**:
+   ```json
+   {"animation_id": "anim_123", "type": "animation"}
+   ```
+
+2. **Simple ID**: `anim_123`
+
+3. **URL Format**: `https://example.com/animation/anim_123`
+
+### State Management
+- **Riverpod**: Reactive state management
+- **Providers**: Separated business logic
+- **State Classes**: Immutable state with when/orNull methods
+- **Error Handling**: Comprehensive error states
+
+## 📱 User Interface
+
+### Cache Management Page
+- Real-time cache usage visualization
+- Progress indicators and statistics
+- Action buttons for cache operations
+- Individual animation management
+- Warning indicators for cache limits
+
+### QR Scanner Page
+- Full-screen camera preview
+- Custom scanning overlay
+- Permission handling
+- Real-time scanning feedback
+- History access
+
+### Media Page (Enhanced)
+- Animation grid with download status
+- QR scanner integration
+- Cache management access
+- Download/playback functionality
+
+## 🧪 Testing Coverage
+
+### Unit Tests
+- **QR Service**: Parsing logic, history management
+- **Cache Service**: File operations, size management
+- **Use Cases**: Business logic validation
+- **Repository Implementations**: Data layer testing
+
+### Widget Tests
+- **Cache Status Widget**: UI state rendering
+- **QR Scanner Overlay**: Visual component testing
+- **Cache Management UI**: User interaction testing
+
+### Integration Tests
+- End-to-end QR scanning workflow
+- Cache management scenarios
+- Offline behavior validation
+
+## 📚 Documentation
+
+### User Documentation
+- **Caching and QR Guide**: Comprehensive usage guide
+- **Testing Guide**: Test structure and execution
+- **API Reference**: Technical documentation
+
+### Developer Documentation
+- **Architecture Overview**: System design explanation
+- **Implementation Details**: Technical specifications
+- **Testing Strategy**: Test organization and best practices
+
+## 🚀 Usage Scenarios
+
+### Scenario 1: QR Code Scanning
+1. User navigates to QR scanner
+2. Scans QR code with animation ID
+3. System validates and downloads animation
+4. User redirected to AR page
+
+### Scenario 2: Cache Management
+1. User accesses cache management
+2. Views current cache status
+3. Optimizes cache or clears specific items
+4. Monitors storage usage
+
+### Scenario 3: Offline Usage
+1. User downloads animations while online
+2. Accesses cached content offline
+3. System gracefully handles network issues
+
+## 🔒 Security & Performance
+
+### Security Considerations
+- Input validation for QR content
+- Safe file operations with error handling
+- Permission management for camera access
+
+### Performance Optimizations
+- Efficient file I/O operations
+- Lazy loading of cache metadata
+- Background cleanup operations
+- Memory-conscious UI rendering
+
+## 📋 Dependencies
+
+### Core Dependencies
+- `flutter_riverpod`: State management
+- `get_it`: Dependency injection
+- `injectable`: Code generation for DI
+- `dio`: HTTP client
+- `camera`: Camera functionality
+- `permission_handler`: Permission management
+- `shared_preferences`: Local storage
+- `equatable`: Value equality
+- `go_router`: Navigation
+
+### Development Dependencies
+- `build_runner`: Code generation
+- `mockito`: Testing mocks
+- `flutter_test`: Testing framework
+- `flutter_lints`: Code quality
+
+## 🎯 Key Achievements
+
+### ✅ Requirements Met
+1. **Local caching strategy** with size/TTL policies
+2. **QR scanner workflow** with camera overlays
+3. **Cache management UI** with status indicators
+4. **Offline fallback behavior** for downloaded content
+5. **Comprehensive tests** for QR parsing and cache services
+6. **Documentation** for usage scenarios
+
+### 🏆 Technical Excellence
+- **Clean Architecture**: Proper separation of concerns
+- **Test Coverage**: Comprehensive unit and widget tests
+- **Error Handling**: Robust error management
+- **Performance**: Optimized file operations
+- **User Experience**: Intuitive and responsive UI
+- **Maintainability**: Well-structured and documented code
+
+## 🔮 Future Enhancements
+
+### Planned Features
+- Cloud sync for cache across devices
+- Advanced QR code formats
+- Predictive content preloading
+- Enhanced analytics and insights
+- Background download management
+
+### Technical Improvements
+- Integration with flutter_cache_manager
+- Advanced compression algorithms
+- Performance monitoring
+- Automated testing pipelines
+
+## 📝 Notes
+
+This implementation provides a solid foundation for caching and QR functionality in the Flutter AR app. The modular architecture allows for easy extension and maintenance, while the comprehensive testing ensures reliability and robustness.
+
+The code follows Flutter best practices and modern development patterns, making it suitable for production use and future enhancements.